The present invention relates to a method and to a two-drum winder for the winding of endlessly fed webs, and particularly webs of paper from roll slitting machines, with the formation of individual wound rolls.
The individual wound rolls lie on two carrier drums, arranged parallel to each other, i.e. an arriving first carrier drum and a departing second carrier drum with respect to the wound roll located in the carrier drum bed thereof and the roll is driven by the drums during the winding process. Then the completely wound roll is lifted off and the web is pressed at a first holding point against the wound roll and at a second holding point against one of the two carrier drums. The web is then stretched over a knife between the two holding points and thereby cut off. The finished wound roll is now removed, and the starting end of the new web is driven back in the direction opposite the web feed direction by means of compressed air and it is taken up by a new winding core which has been made ready, and wound up.
This type of web winding is known from Austrian Pat. No. 332,214, which corresponds to U.S. Pat. No. 3,841,578. There the web travels upward from below between the carrier drums and onto the roll to be wound. The web wraps around a part of the second carrier drum as seen in the direction of winding. The new winding core is, however, not placed on top of the carrier drums but is applied from below to the carrier drums and is pre-wound there. Thereupon the two carrier drums are moved apart, the pre-wound winding core is brought upward into the carrier-drum bed and the two carrier drums are again brought to the required narrow distance from each other. Since the carrier drums are several meters long and are normally also driven, this means an expensive construction. Furthermore, glue must be applied to the web so that the end of the new web produced by the cutting process is in each case taken up by the new winding core and is wound. Nevertheless, the starting end of the newly cut web may undesirably not remain attached to the new winding core, but may instead slide away downward past the new winding core.
U.S. Pat. No. 3,918,654 shows a double-drum winder in which the web is not passed upward from below between the carrier drums but is instead conducted over the two drums. The new winding core is in each case applied from above onto the web and is pressed together with the web into the drum bed. In this case also, gluing of the web of paper is necessary so that it be grasped by the new winding core and then wound. After completion of a wound roll, the web is cut by a knife that is pushed through the section of the web in the upward direction between the two drums. The web is moved, between the two drums, around the lower section of the new winding core. Only a small amount of space is available for the knife between the drums and the device for the actuation of the knife is complicated. Furthermore, the knife must also be frequently replaced since it can cut the web on the winding core only when it is extremely sharp. Furthermore, there is also the danger that, despite the gluing, the starting end of the new web will not be wound by the winding core, but will instead move away. In addition to this, with both of the known methods and the double-drum rollers, there is a danger that the carrier drums and the web of paper being dirtied by glue so that the web will remain stuck in undesired fashion in the machine and will be damaged.